1. Field of the Invention
This invention relates to synthetic resin fittings used in an electrical service system for interconnecting wire carrying conduits to electrical boxes, and more particularly, for interconnecting a synthetic resin electrical box with a synthetic resin externally corrugated conduit.
2. Brief Description of the Prior Art
In electrically wiring a commercial or residential facility, wall or ceiling mounted electrical service boxes are provided and various types of electrical conductors are extended from these boxes to outlets or points of electrical usage throughout the facility. A practice increasingly favored in many installations is to encase or sheath the electrical conductors in various types of flexible conduits. These conduits are frequently constructed and dimensioned so that they may be easily bent or curved to facilitate selective directional extension of the conductors and the enclosing conduit as may be required in the course of installation.
One technique used to impart flexibility without significant loss of mechanical properties in such conduit is the practice of forming the conduit in corrugated form so that the corrugations facilitate flexture of the conduit in substantially any direction without cracking or weakening. More recently, and increasingly, such conduit has been formed from various synthetic resin materials.
Since the time required for, and the ease of, installation of the described electrical systems are very important considerations in their usage by electricians, improvements in components of the system which improve the ease of installation or reduce the time required to incorporate such components are of substantial value.
In systems of the type described which include electrical boxes and externally corrugated conduits in which the conductors are enclosed, a means of connecting the conduit to the box is required. To this end, various types of connector fittings have heretofore been proposed and many of those proposed have been utilized. One such type is that which is illustrated and described in U.S. Pat. No. 4,248,459, assigned to the assignee of the present application. The connector fitting there depicted is a synthetic resin structure which has a cylindrical portion of tapered configuration so that it may be snapped into a circular opening formed in an electrical box. The fitting carries grooves or ridges adapted to engage the external corrugations on a conduit of the type described so that the conduit is engaged with the electrical box when the fitting has been snapped into place in the manner described.
Other fittings of this general character and mode of usage are those which are illustrated and described in U.S, Pat. Nos. 3,831,985; 3,953,555 and 1,830,250.